Roughly two-thirds of Windows Chrome users have other applications on their machines that interact with Chrome, such as accessibility or antivirus software. In the past, this software needed to inject code in Chrome in order to function properly; [...] With Chrome extensions and Native Messaging, there are now modern alternatives to running code inside of Chrome processes....

We probably shouldn't run software that injects code into any browser. Also, the so called anti virus and the extensions and toolbars that come with them weaken and expose your security rather than protect you.

If you are running Windows 10 and have Windows Defender you are already better protected than if you were running antivirus software.

I never installed any anti-virus software till date and also disabled Defender on Win 10. As long you don't go around running executable files you have no chance of infecting and also running uBO + uMX on Chrome and Firefox takes cares of any malware/adware potentially coming across during the browsing session. If you want to install a particular program, download it from the dev himself and scan it on virustotal.com so you know what you're getting into.

If the dev offers files hashes, get them and compare them with the ones found in the program you downloaded, as long as they match, the program isn't modified and is the same as the one provided by the dev himself.